New meta-analysis: No link between vitamin D and pancreatic cancer

According to a new meta-analysis, there is no link between vitamin D and pancreatic cancer.

The cause of pancreatic cancer is unknown, though there are some known risk factors. These include older age, smoking, type II diabetes, obesity, sedentary lifestyle and chronic pancreatitis.

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One problem with pancreatic cancer is that when it’s discovered, intervention is often no longer possible. So researchers are very interested in risk factors to make sure we understand all the preventative measures we can take.

As most here know, researchers are very interested in the anti-cancer effects of vitamin D, by way of influencing the proliferation, differentiation and apoptosis of cells. There is particularly good data showing that vitamin D deficiency may play a role in breast, colon and prostate cancers. The extent of benefit of getting enough vitamin D in protecting against these diseases is not known, but researchers have high hopes that better sun exposure habits and vitamin D supplementation can significantly reduce incidence of these three cancers.

One cancer that has cast a modicum of doubt on vitamin D is pancreatic cancer. There are a few studies that show that people with a high vitamin D level or intake may have a slight increased risk of developing pancreatic cancer compared to lower intakes. Vitamin D enthusiasts counter that since there is benefit in taking vitamin D against the three common cancers of breast, colon and prostate, if there is any risk of getting pancreatic cancer, it’s worth the risk in the benefit you’re getting.

But is there an increased risk of pancreatic cancer? Sure, a few studies do show an increased risk, but what do all the studies combined show? Recently, researchers from the Chinese Academy of Medical Sciences and Peking Union Medical College looked at this very question and did a meta-analysis on vitamin D and pancreatic cancer.

The researchers searched the PubMed, Web of Science and Embase databases for literature on pancreatic cancer and vitamin D. Studies were included in their meta-analysis if they measured vitamin D intake or 25(OH)D levels and looked at pancreatic cancer as the outcome of interest.

The researchers found nine studies that met inclusion criteria. Three of them measured vitamin D intake, while the other 6 measured vitamin D levels.

The researchers took a look at the odds ratio from each study. The odds ratio (OR) was calculated by comparing the pancreatic cancer incidence of the highest category of vitamin D levels/intake to the incidence in the lowest category of vitamin D levels/intake. They then pooled the ORs of the studies together.

This is what they found:

There was a slight but statistically non-significant increased risk of getting pancreatic cancer if you were in the highest category of vitamin D compared to lowest (OR=1.14, 0.896–1.451).

When they only looked at blood levels and excluded intake studies, there was also a slight but statistically non-significant increased risk of getting pancreatic cancer if you were in the highest category of vitamin D compared to lowest (OR=1.04, 0.93–1.17).

The researchers concluded,

“In conclusion, this meta-analysis showed no association between vitamin D level and risk of pancreatic cancer. Increased dietary vitamin D or circulating concentrations of 25OHD did not increase the risk of pancreatic cancer based on the evidence from the current published studies.”

So, based on current evidence, it appears that pancreatic cancer is not even a concern when we look at the cost-benefit analysis of vitamin D.

12 Responses to New meta-analysis: No link between vitamin D and pancreatic cancer

We know that optimal vitamin D levels play a protective role in prevention of diabetes II.

And diabetes II is the third modifiable risk factor for pancreatic cancer after cigarette smoking and obesity. Epidemiological investigations have found that long-term diabetes II is associated with a 1.5- to 2.0-fold increase in the risk of pancreatic cancer.

To: Rita I think you took this study the wrong way. I think the studies intent was to prove if higher Vitamin D levels caused an increase in pancreatic cancer. The answer was no it does not. I am sure none of these studies used enough to say whether or not Vitamin D helps or not. We at the VDC all no better without the studies.

I understood the intent of the study. And, this isn’t the first study to show a slight but statistically non-significant increased risk of getting pancreatic cancer if you are in the highest category of vitamin D blood serum levels compared to lowest.

And it is this slight, but non significant risk which perplexes me.

Because, as I am seeing it:

As optimal vitamin D levels are essential for healthy glucose/insulin levels; and long term diabetes II is a significant risk factor for developing pancreatic cancer, I would have thought that anything that treated or prevented diabetes II would also keep pancreatic cancer at bay…And, therefore, I am wondering WHY even the statistically non-significant increased risk of getting pancreatic cancer with higher 25(OH)D levels rather than lower….

I might be missing something…I hope someone will enlighten me…this vitamin D/pancreatic cancer thing has piqued my interest for some time now.

I have a high history of diabetes I and II on both sides of my family line.

BTW, Ivy, we at the VDC do KNOW better without the studies; however, mainstream medicine demands such studies; and without them we are all no better off (in terms of mainstream vitamin D acceptance, and this is MY life mission). 😉

One of the problems with many of the studies included in the meta-analysis is that they were nested case-control studies from cohort studies in which serum 25-hydroxyvitamin D levels were determined from blood drawn at the time of enrollment. Follow-up periods were as long as 17 years. Serum 25-hydroxyvitamin D levels change with time and adversely affect the findings: Grant WB. Effect of interval between serum draw and follow-up period on relative risk of cancer incidence with respect to 25-hydroxyvitamin D level; implications for meta-analyses and setting vitamin D guidelines. Dermatoendocrinol. 2011;3(3):199-204. Grant WB. Effect of follow-up time on the relation between prediagnostic serum 25-hydroxyitamin D and all-cause mortality rate. Dermatoendocrinol. 2012;4(2):198-202.

In my opinion, the authors dumped the data into a vat, turned the crank, and looked at the results. They provided no insight into the topic. Their finding should be taken with a grain of salt.

Dr. Grant, this is certainly reassuring to read. And, it does make sense to me. Every time I read a negative study on D and pancreatic cancer, I would shake my head in disbelief. The connection between diabetes II and pancreatic cancer is so strong that I found it difficult to believe that anything as helpful as vitamin D has been shown to be with respect to diabetes wouldn’t also be as helpful in preventing pancreatic cancer.

Good question. For these style of meta-analyses, researchers are not able to define highest category because each study they include in their meta-analysis uses different cutoffs.

For example, let’s say you pooled together 10 studies that all looked at the risk of pancreatic cancer and vitamin D levels. Each study split their population into quartiles of vitamin D levels. Even though they all use quartiles, they’re all going to have different cutoffs for these quartiles. For example, the highest quartile in Iceland might be something like 30-50 ng/ml, while the highest quartile in Brazil might be 35-70 ng/ml.

When all 10 studies are pooled together, the researchers do not put all the people in a big pot and redefine quartiles (or could be tertiles, etc). They simply look at the odds ratio of highest vs lowest categories of each study, take into account population of each study so they know how much weight to place on each, and then see what the combined odds ratio of all 10 studies is.

The pro to an meta-analysis is that you get to answer the question, “What does all the research say?” All the research shows there’s no correlation between vitamin D and pancreatic cancer (while some specific studies says there is), and there’s no difference between being in lowest category and highest.

The con is that it doesn’t provide insight into some nuances on the topic, as Dr Grant notes above, and as you ask about (“What is the highest category?”).

In the context of pancreatic cancer-vitamin D, I find the paper useful because there are a few studies that show increased risk of pancreatic cancer with higher vitamin D levels. But there are also studies that show the opposite. To put to rest any doubts, we need a study that answers, “What do all of these studies combined say?”

Brant thanks for the answer….however, excuse my ignorance but Dr. C and I believe Grass Roots call for a level of 40-60 ng, so therefore, that is the highest quintile (using your example above.). And, as the other cancers that D3 would be protective (breast, colon etc) these are types of cancer that can be detected, with common screening. However pancreatic cancer is not detectable until it is usually too late. I realize that there is a cost vs. benefit ratio involved but it certainly gives me pause for keeping levels at the recommended levels.

One thing I didn’t explain very well is that the categories in these studies, whether it’s a tertile, quartile, quintile, are not for researchers to decide.

For example, maybe they study a population in Brazil and draw vitamin D levels in every single person. Let’s say the 0th percentile vitamin D level is 7 ng/ml, the 25th percentile level is 15 ng/ml, the 50th percentile is 25 ng/ml, 75th is 35 ng/ml and 100th is 70 ng/ml. Then those are your categories:

Q1: 7-15 ng/ml Q2: 15-25 ng/ml Q3: 25-35 ng/ml Q4: 35-70 ng/ml

In some studies, they do use predefined cutoffs, ie lower than 20 ng/ml, 20-30 ng/ml, above 30 ng/ml, but in this meta-analysis (and in most), since each study has different categories and cutoffs, they simply pool the odds ratio of high vs low from each study, as they have no power to put each individual in a big pot and redefine cutoffs.

Paul McGinnes Have a look at March,April,June July 2013 Newsletters from Hair testing(www.traceelements.com) about the levels of minerals affect the outcome of drug treatment of most Diabetes. the same conditions could affect outcome with Pancreatic Cancer vs Vitamin D Cheers Paul

When it comes to pancreatic cancer, I have only my experience/observation of the identical twin of a person with pancreatic cancer. I met the healthy twin, who worked with me, in September in Arizona. By Christmas he quit his job upon the diagnosis that his identical twin brother had just been diagnosed with advanced pancreatic cancer back in Maryland. My co-worker returned to Maryland to help stabilize and then take over his dying twin’s Computer Consulting business to ensure an income for the upcoming widow and children.

One: My co-worker was chubby, 35-ish, blond and white as a sheet. We were in ARIZONA at 7,000 feet elevation and working with grade school kids. Evidently at recess he stood in the shade. There was no evidence that he had ever been in sunshine, no pinkness, no tan, no tan line, nothing.

Two: Both brothers were computer geeks. Sadly we would all have to admit that most computer geeks we know typically are not interested in sports or outside activities, often stay up all night and sleep all day.

I myself at this time (totally oblivious to the Vitamin D Council’s existence, and completely unaware of Vitamin D and health issues, AND scared cr*pless of ever talking vitamin D pills of any strength–lest I melt my brain or some other horrible fate) was walking shirtless around the football field track every day all fall, all winter (even in the snow), and all Spring to “maintain my tan so that I would not sunburn should I be caught accidently outside the next summer” — as well as for the exercise.

My point is: as merely anecdotal as this episode about my unfortunate friend whose brother has most likely passed away is, the telling of it is more humanly relevant, reliable and authentic than the quacks that performed lobotomies in the 1930′ and 40’s and maybe even into the 50’s and collected handsome payments for slicing people frontal lobes away from the rest of the brain with a knife hammered through the eye socket — lobotomies that were based on “science”.

Real science is compatible with common sense. Fear of sunshine does not pass the basic test of common sense.

There are always flies in the ointment of research which makes much of it merely “so-called research”.

The FLY: When people start feeling sickly or feeling that something is not “right” they tend to start looking for cheap, handy, no-doctor-involved, self-medicating solutions. Some of those are, but not limited to, better bowel movements by taking bran / metamusil / prunes / etc. and starting or increasing vitamin intake, or starting new specialty vitamin (like C, D, K, B*, etc) and health-nut supplements of various kinds (St John’s Wort, etc) or food changes like more mushrooms or more carrots or more of whatever miracle food has recently been yakked about in the media.

When that person finally goes up the chain of doctors (months or years after starting his self-help cures) and gets a conclusive diagnosis of, say, pancreatic cancer or whatever, that person self-divulges into the medical record the large amounts of vitamins / minerals / herbs they are currently taking. Lab blood tests at the point of diagnosis reflect the fairly recent upping of supplemental intake — at which time the fly squats down and takes a dump.